ex1441.cpp

来自「practice c++, it is from the book http:/」· C++ 代码 · 共 49 行

//  Programming with C++ by John R. Hubbard
//  Copyright McGraw-Hill, 1999
//  Example 14.1 on page 

#include <cassert>
#include <iostream>
#include <vector>     // defines the Standard vector<T> class template
using namespace std;
typedef vector<double> vec;
typedef vector<bool> bits;
vec projection(vec& v, bits& b);
void print(vec& v);

template <class T>
void copy(vector<T>& v, const T* x, int n)
{ vector<T> w;
  for (int i=0; i<n; i++)
    w.push_back(x[i]);
  v = w;
}

vec projection(vec& v, bits& b)
{ int v_size = v.size();
  assert(b.size() >= v_size);
  vec w;
  for (int i=0; i<v_size; i++)
    if (b[i]) w.push_back(v[i]);
  return w;
}

void print(vec& v)
{ int v_size = v.size();
  for (int i=0; i<v_size; i++)
    cout << v[i] << "  ";
  cout << endl;
}

int main()
{ double x[8] = { 22.2, 33.3, 44.4, 55.5, 66.6, 77.7, 88.8, 99.9 };
  vec v;
  copy(v, x, 8);
  bool y[8] = { false, true, false, true, true, true, false, true };
  bits b;
  copy(b, y, 8);
  vec w = projection(v, b);
  print(v);
  print(w);
}